Background The use of diagnostic ultrasound by physiotherapists is not a new concept; it is frequently performed in musculoskeletal physiotherapy. Physiotherapists currently lack accurate, reliable, sensitive and valid measurements for the assessment of the indications and effectiveness of chest physiotherapy. Thoracic ultrasound may be a promising tool for the physiotherapist and could be routinely performed at patients’ bedsides to provide real-time and accurate information on the status of pleura, lungs and diaphragm.

Methods This is a narrative review. This review refers to lung and diaphragm ultrasound semiology, and how thoracic ultrasound should be used in the physiotherapist’s clinical decision-making process.

Results Lung ultrasound enables diagnosis of pleural effusion, pneumonia, atelectasis, pulmonary contusion, pulmonary oedema and pneumothorax with high sensitivity and specificity. Sonographic evaluation of the diaphragm enables to quantify its motion, thickness and contractility. Understanding the lung ultrasound fundamentals and basic signs allows an accurate assessment of pleura, lung parenchymal and diaphragm.

Lung ultrasound provides information on the lung aeration disorders and can guide the physiotherapist’s choice of techniques and parameters in chest physiotherapy.

Indeed, thoracic ultrasound may be helpful to answer clinical questions such as ‘Is only the major airway retaining secretions or is lung consolidation also present?’ and can provide significantly higher accuracies than conventional examinations performed by the physiotherapist.

It is also an excellent tool for pleural assessment and may be a way to clarify indication of chest physiotherapy in pleural effusion. Diaphragm sonography enables to highlight in real-time diaphragm response to all chest physiotherapy techniques that are intended for this purpose.

Thoracic ultrasound should be used in addition to the clinical examination.

Conclusions Diagnostic ultrasound performs significantly better than chest X-rays or auscultation at diagnosing lung deficiencies that are relevant for the physiotherapist. Physiotherapists should use lung ultrasound semiology to guide, monitor and evaluate their chest physiotherapy treatments. This potential new tool for physiotherapists still requires significant development before being used commonly.